Process fob producing n-substitu-



Patented Nov. 19,1940 p v I 2,222,350 UNITED STATES PATENT OFFICEPROCESS FOR PRODUCING N-SUBSTITU- 'I'ION PRODUCTS F MELAMIDTE KarlKeller and Ernst Korten, Frankfort-on-the- Main-Fechenheim, Germany,assignors to I. G.

. Farbenindustrie Aktiengesellschaft, Frankforton-the-Main, Germany NoDrawing. Application July 8, 1939, Serial No.

' 283,454. In Germany July 11, 1938 1 01am. (Cl. 260-248) Our presentinvention relates to a process for and N.N'-tetramethylmelamine of theformula:

producing N-substitution products of melamine. N-substitution productsof melamine have been prepared hitherto only by starting from J} 5triazine compounds. s 5

' According to the present invention N-substitution products of melamineare produced by heat- II L ing a mixture of dicyandiamide and a primaryor secondary amine of the aliphatic, aliphatic- N 1 aromatic,hydroaromatic or aromaticseries to The separation into the'componentsmaybe elevated temperatures in a closed vessel with or carried out forinstance by extraction with ethyl without the addition of a solvent ordiluent of or butyl alcohol whereby melamine remains unnon-acidiccharacter. Thereby besides melamine dissolved. From the filtrate firstlyN-dimethylmixtures of mono-, ,diand poly substitution' aminecrystallises out, then after apartial evapoproducts of melamine areobtained, the proporration the N.N'-tetramethylmelamine. One may 5 tionof the individual components being delikewise dissolve the crude productin hot formic pendent in a far-reaching'manner upon the re acid of about10% strength, remove small quanaction conditions applied. titis ofinsoluble, products, consisting mainly of The formation of theN-substitution products melamine, and cool the solution to room temofmelamine occurs. apparently with passage perature, whereby the formateof melamine sepa-l 20 through different intermediate stages, probablyrates and is filtered ofi. The liquor is neutralized for examplesubstitution products of guanidine, with ammonia, wherebyN-dimethylmelamine biguanide or cyanamide are first formed. Whenseparates, which after having been purified by using primary aminesapparentlybesides the normeans of water and alcohol melts at 307. to308,

mal melamine derivatives as ,b'y-products sub- From the neutral motherliquor after standing stitution products of isomelamine are formed in ormore rapidly after the further addition of small quantities. a ammoniathe N.N-tetramethylamine of melting The mixtures thus obtained may beused as point 220 to 222separates. such, for instance for the productionof alde- By'varying the reaction conditions, for instance 'hydecondensation products, or they may be by using an excess ofdimethylamine, the yield of separated .into the individual components acN-dimethyland N.N-tetramethylmelamine can cording to the usual methods,for instance by be increased and that of melamine diminished.

dissolving them in suitable solvents, in some Example 2 casesadvantageously after conversion into the Salts of t bases, A mixture of126 parts of dicyandiamide and 35 In order to further illustrate ourinvention the 292 Parts of butylanfine is heated o about 7 followingexamines are given t parts being hours at 250 to 280 1n an ironautoclave. When by weight and ,1 temperatures in degrees cool thereaction mass is repeatedly extracted grade. with ether. In this mannerabout 80 parts of a Example 1 crystalline residue and an etherialsolution ar 40 obtained whichmay be worked up for instance as To 300parts of powdered dicyandiamide 90 follows:

Parts f liquid dimethylamine are added in a (a) The res1due is extractedwith alcohol,

closed vessel. The mixture is slowly heated to I F parts of whit-ecrystals remam, about 120 whereby a strong exothermic reaction conslstmgmamly. of melamme a little 45 occurs and the reaction temperature risesto amount of melam' alcPhohc solutlon 15 about 220. Then the mass isslowly cooled and evaporated n the P 3 15 extracted with about 320 partsof a crude product ispbtained benzene. There remain about 32 parts ofmonoconsisting mainly of melamine, N-dimethylbutylmelamme of theformula:

melamine of the formula: NH-CrHv 50 on: 1 I III HzN-C\ /C-NH1 t om N/ 55N N as a white crystalline powder melting at 180 to i The benzenesolution contains a further a reaction product of a minor nitrogencontent. 60 N (b) The aforesaid etherial solution is evapm 6o as a whitecrystalline powder of 245 to 247 melt- 4 ing'poirit. It has a nitrogencontent of 30.2% and a chlorine content of 12.9%. The free base may beobtained by digesting the hydrochloride with a sodium carbonate solutionand extracting with ether. It is a light sirup which solidifies 'whencool with formation of crystals.

4 Example 3 200 parts of finely powdered dicyandiamide are mixedwith-126 parts of monobutylamine and 50 parts of one of the commercialactivated bleaching earths and the mixture is slowly heated in a closedvessel to about 200. The temperature is maintained for about 15 hours,the pressure ascending to about atmospheres. When cool the formedcrystalline mass is extracted with methanol. The. residue, about 140parts consists of the employed bleaching earth, melamine anda littlequantity of melam. The methanolic solution-is evaporated and theremaining crystalline'mass is digested with ether, filtered oflf andwashed with ether. In this manner -65 parts of monobutyl melamine ofabout 185 melting point are obtained, of. the foregoing example. Theaforesaid etherial filtrate is evaporated and held at slightly reducedpressure for. some time at to in order to remove gaseous ingreclients.In this mannerabout 70 parts of a viscons sirup are obtainedconsistingaccording to an analysisprobably mainly of a tributylmela-vmine.

. amine remain.

Example 4 A mixture of 252 parts of strongly dried and finely powdereddicyandiamide, 146 parts of isobutylamine and 150 parts of xylene isheated in a closed vess'el while stirring at to The pressure increasesto about 38 atmospheres. When cool the reaction mixture may be worked upin a similar manner as described in the Example 2. Thus'are obtainedabout 116 parts of melamine, about '7 parts of melam, about 45'parts ofmonoisobutylmelamine of 160 to 166 melting point, the hydrochloride ofwhich melts at 260 to 266", about .95 parts of N.N'-diisobutylmelamineas a sirup, which solidifies when cool in a crystal line form, themonohydrochloride of which melts at about 230 to 235. Finally 20 to 25parts of a mixture of symmetrical triisobutylmelamine with byproducts ofa minor nitrogen content are obtained. p

' Example 5 A mixture'of 126 parts of dicyandiamide and 290 parts ofaniline is heated in an autoclave for 10 to 12 hours while stirring atto whereby the pressure" rises to 20 atmospheres.

'When cool the excess ofaniline is removed from the formed crystal pulpby steam distillation. The residue is evaporated and extracted withboiling alcohol, whereby about 53 parts of mel- From the alcoholicsolution by fractionated crystallisation monophenylmelamine,diphenylmelamine, triphenylmelamine and a crystalline substance, solublein ether, melting at 80. to 85 of a nitrogen content of about 29.5% canbe isolated, I

We claim: Process ,for producing N-substitution products b of melamineWhich consists in heating a mixture of dicyandiamide and in the freestate an amine selected from the classconsisting of those of the KARLKELLER. ERNST KORTEN.

